Real space Green´s function for stacked structures consisting of bianisotropic materials

A crucial point in the Method of Moments (MoM) analysis of passive microwave devices is the knowledge of Green´s functions associated with the problem under consideration. In a variety of applications materials with complicated material equations are used; these lead to rather complicated Green´s functions. In order to cover such materials we present a numerically efficient approach for the construction of spatial domain Green´s functions for layered structures involving fully bianisotropic materials. First we show how spectral domain Green´s functions can be constructed by utilizing an Eigenoperator formulation of the field equations which is capable of handling fully bianisotropic materials. The spatial domain Green´s functions are then obtained by application of an inverse Fourier transform. Contributions representing guided waves and quasi-static terms are subtracted from the Green´s functions and are transformed individually into real space. This extraction leads to a regular and well-behaved remainder function which can be transformed numerically. The proposed procedure moreover provides physical insight into the problem, e.g. it allows us to study the behaviour of guided waves in layered, bianisotropic structures.